Co-occurrent substance use and violence compromises the health, safety, well-being, and life chances for adolescents. Although research has identified important risk and protective factors for substance use and violence independently, less is known about risk and protective factors for their co-occurrence. The purpose of the proposed research is to outline those risk and protective factors at the individual and neighborhood levels that are predictive of co-occurring substance use and violent behavior. This research represents an attempt to analyze existing data to yield new insights into the epidemiology of co-occurring substance use and violence among urban adolescents. Data will come from the Boston Youth Survey 2008 (BYS08), a citywide survey of 9th to 12th grade students in all public schools in the city of Boston. Classrooms within each school have been randomly sampled for inclusion. The 45-minute data collection instrument inquires about various aspects of youths lives, including: (1) exposure to and involvement in aggressive and violent behavior, (2) involvement in school and extra-curricular activities, (3) contact with and trust in adults, (4) emotional well-being, (5) use of alcohol, tobacco, marijuana, and other drugs, and (6) neighborhood characteristics, e.g., collective efficacy. Analyses for the proposed work will examine: the lifetime and past-month prevalence of substance use (i.e., alcohol, tobacco, and marijuana), recent perpetration of violent and aggressive behaviors (i.e., physical aggression toward peers, physical aggression toward siblings, dating violence, and bullying), and a broad range of risk and protective factors for risk behaviors. Because students are nested within both schools and neighborhoods, and because we are interested in exploring how both neighborhood- and individual-level factors modify risk for substance use and violent behavior, we will use multi-level statistical models to quantify the degree to which risk and protective factors are associated with co-occurrent substance use and violent behavior. The Human Subjects Committee at Harvard School of Public Health has approved the research protocol for the BYS08. What is learned from this research is practically useful in that it will be disseminated to those working to prevent risk behaviors among Boston adolescents, and can also inform the work of those in similar locales. PUBLIC HEALTH RELEVANCE: The proposed work represents an attempt to analyze existing data to yield new insights into the epidemiology of co-occurrent substance use and violence among urban adolescents. It will generate new, practical information about risk and protective factors at the neighborhood and individual levels that give rise to co-occurrent substance use and violent behavior among urban adolescents. The results are immediately useful to those working locally to prevent risk behaviors among Boston youth, and can also inform the work of those in similar locales.